Sextant



lime 1945- Jqv. HORR 2,378,770

- SEXTANT Filed June 22, 1943 2 Sheets-Sheet 1 INVENTOR John 01"? J. V.HORR June 19, 1945;

SEXTANT Filed June 22, 1943 2 Sheets-Sheet 2 INVENTOR .fohn VfiorrATTORNEY Patented June 19, 1945 UNITED STATES. PATENT OFFICE h SEXTANTJohn. V. Horr, North Tarrytown, N. Y., assi'gnor to Einson-Freeman 00.,Inc., Long Island City,

N. Y.,a corporation of Delaware Application June 22, 1943, Serial No.491,779

2 Claims. 7 (CI. 33-70) 7 My present inventionrelatesgenerally; tomeasuring instruments and has particular reference to sextants. v 7; l i

A general object of the invention is to provide certain structuralimprovements and innovations which simplify the process of manufactureand which make lit possible to produce sextants more expeditiously andeconomically.

The structuralimprovements whichI have de vised lend themselvesreadilytovthe processes of quantity manufacture, and are primarilyintendedto make it possible to manufacture sextents in large numbers andat lowvcost.

It is a more particular object of the invention to provide aconstruction which permits the extensive use of ordinarysheet materialwhereby relatively simple procedural steps, such as stamping, cutting,printing, and the like may be resorted to. While the invention is bynomeans restricted to the userof any particular material, the presentimprovements are of such a character that ordinary fiatsheets ofcardboard stock, or equivalent relatively inexpensive sheet material,may be satisfactorily,employed. Notwithstanding the fact that a sextantis a relatively delicate instrument requiring accuracy in thearrangement of parts and in the movements provided for, an instrumentconstructed in accordance with the present invention is adequatelyprecise and, reliable for most normal purposes and is unusually staunchand rigid. l l

Among the numerous respects in which'a sextant structure has beenimproved by means of .the present invention are the mode of pivoting theswinging arm or alidadeto the basic frame, the manner in which the indexportion of the alidade is assembledthe simplified manner in ,which ahandle is formed and braced, the mode of pivoting a screen or screens toan edge portion of the frame, the, manner in which a level-glass unitmaybe optionally employed, and the general way in which the structure as awhole is simplified and is nevertheless adequately reinforced.

I achieve the foregoing objects and advantages, and such other objectsand advantages as may hereinafter appear or be pointed out, in themanner illustratively exemplified in the accompanying drawings in which:

Figure 1 is a front view of a sextant constructed in accordance with thepresent invention;

Figure 2 is a rear view of Figure 1;

Figure 3 is an enlarged cross-sectional view taken substantially alongthe line 3-3 of Figure a ,,Figure 4 is an enlarged cross-sectional viewtaken substantialy along the line 4-4 of Figure 1; Figure 5 is anenlarged cross-sectional view taken substantiallyfalong the line 5-5 ofFigure 1; Figure 6 isan enlarged cross-sectional view takensubstantially along the line 6-6 of Figure 1; Figure 7 is an enlargedfragmentary view of the edge portion of the frame with which one or morescreens maybe associated;

Figure 8 is an end view taken from then'ght of, Figure 7; and a Figure 9is a cross-sectional View taken substantially along the line 9-9 ofFigure 7.,

, The main or body element of the sextant illustrated on theaccompanying drawingsis a frame which consists of a flat sheet ofsubstantially triangular contour having an arcuate index edge 2| withdegree markingsor graduations 212 thereon. The sheet 20 may be composed,if desired,

of inexpensive cardboard stock. In its midportion, it is provided withtwo substantially triangular openings 23 and 24. Aportion of' thecut-out material isin each caseretained in only partially-severedandhence hinged relationship to the frame 20, thereby defining tworearwardlydeflected wings Ziand 26 respectively. The openings 23 and 24are preferably so formed and spaced that the wings 25 and 26 will lieinparallel planes perpendicular tothe frame 20; This rear surface of theframe 20, while the bracing from the plane of the frame 20.

portion 21 extends obliquely rearwardly away The brace 21 may beconveniently provided with spaced slots which engage frictionally withshoulders 30 formed on the wings 25 and 26.

Pivotally associated with the frame 20 in concentric relationship to thegraduated edge 2| is a swinging arm or alidade having a pivot portion atone end and an index portion at the opposite end. i l

The index portion is composed of three interconnected superposed pliesof fiat sheet material, such as cardboard or the like,the two outerplies 3i and 32 (see Figures 1, 2 and 3)' sandwiching the frame 20between them, the intermediate ply 33 having an inner edge whichconforms in curvahesive means or otherwise, and conjointly define astaunch and rigid index portion which may be shifted along the graduatededge 2! as the sextant is used, the interengagement being firm andaccurate. Readings may be taken through the opening 34 with unusualprecision, because of,

the abutting relationship between the graduated edge 2| and the verniergraduations on the intermediate ply 33.

The pivot portion of the alidade is similarly composed of three plies ofsheet material such as cardboard or-the like, the outer plies 35 and 36-'(see upper portions of Figures 1, 2 and'3) lying on opposite sidesrespectively of the frame 20, the intermediate ply 31 being snuglyaccommodated within a pivot opening of circular shape provided for thepurpose in the frame 20. The intermediate ply 31 thus constitutes ajournal portion and is preferably a disc of circular contour.

The three plies 35, 36 and 31 may be held towith respect to the grain ofthe other, and this results in effecting staunchness and rigidity ofunusual character.

It is sometimes desirable to provide the sextant with one or morescreens which may be swung into and out of the optical axis of thedevice to intercept and filter the rays of light which pass from theindex mirror 49 to the horizon mirror 43. I have illustratively showntwo such screens 49 and 50 (see Figures 7, 8.and 9) and an improvedmanner in which these screens may be pivotally associated with anedgeportion of the frame 20. As shown most clearly in Figure 8, the edgeportion to which the screens are to be pivoted is composedof three pliesof sheet material.

, The outer ply is constituted of a portion of the,

gether in any convenient manner, by adhesive means or otherwise, and theinterconnection may be enhanced by nails or similar elements 38 whichextend through all three plies and thence into a block 39 (of wood orthe like) which carries the usual index mirror 49. l

The body portion 4| of the alidade-may be conveniently formed of onepiece of sheet material, such as cardboard or the like, with the outerply 3| of the index portion and the outer ply I of the pivot portion.

The other essential elements of the sextant structure are the telescope42 and the so-called horizon mirror 43. These elements are permanentlysecured. in proper relationship to the front face 29! Preferably, thetelescope 42 consists of atube of cardboard or the like firmly anchoredin a block 44 which may be composed of woodand which is held in positionby adhesive means,

preferably with the aid of nails 45 or similar fasteners. At theeye-piece end of the telescope I prefer to insert an apertured plug ordisc 46 which reduces the size of the peep opening, and at the oppositeend of the telescope,

I provide a nail or pin 4'! which extends diametrically across the tube42 and serves to-facilitate the sighting procedure.

Similarly, the horizon mirror 43 may be conveniently mounted on a block48, composed of wood or the like, this block. being permanently securedto the frame 20 by adhesive means or the like, with or without the aidof nails or similar additional fasteners.

In order to rigidify the frame 20 and to retain the telescope and thehorizon mirror in proper predetermined relationship at all times, theupper portion 29 of the brace is of such a size and shape that itextends behind at least a portion of the block 44 which supports thetelescope, behind at least a portion of the block 48 which carries thehorizon mirror, and across the entire area between them, as indicatedmost clearly 'the like, the grain of one is arranged transversely siredregion of the frame 20.

ally mounted within a suitable slot formed in this three-ply edgeportion. Because the screens are of relatively thin material, such ascelluloid or the like, a firm engagement within the slot is assured bythe unique arrangement of the elements (as shown most clearly in Figures7 and 8) whereby one side of the slot is defined by the alignedshoulders 55 formed on the plies 20 and 5|, while the opposite side ofthe slot is defined by an opposed shoulder 55 formed on the intermediateply 29. Each of the shoulders 55 is preferably provided for by cutting aslot of substantial dimensions in the corresponding ply, and theshoulder 56 may similarly be formed by means of a slot in theintermediate ply 29, but these cut-out portions need not be of criticaldimensions because the staggered relationship of the plies, as shown inFigure 8, provides a resultant slot of adequately minute widthtoiaccommodate the'screen or screens 49 and 50 in the proper manner.

The actual pivoting of these screens may be conveniently established bymeans of a pivot pin 52 which extends across the slot and has itsopposite end portions accommodated within aligned recesses 53 formed inthe'intermediate ply 29, the pin 52 being permanently held in properposition by the sandwiohing action of the outer plies 29 and 5|.

A screen or screens of similar character may be provided for in similarfashion in any other de- It is an additional feature of the presentconstruction .to provide a means for removably securing an optionallevel-glass unit to the frame 20. This unit may consist, for example, ofa block 51, of wood or the like, within which the level-glass itself 58is permanently secured, a mirror 59 being carried by the block 51' at asuitable'angl'e to make the level-glass visible to the user of thedevice when looking through the telescope 42. To provide for theremovable attachment of this unit, the frame 29 is provided with a slit60, and the level-glass unit carries adjustable fasteners which may beassociated with this slit. I prefer to employ as fasteners one or morescrew-threaded elements 6| having enlarged heads, such as the loopedhead shown in Figure 5 at 62. The screwthreaded engagement permits thesefasteners to be rotated through When adjusted to bring 'the'heads 62into alignment with each other and preventing withdrawal of thefasteners thus locking the level-glass unit to the frame.

In general, it will be, understood that the pose of describing thegeneral nature of the present structural improvements may be modified bythose skilled in the art without departing from the spirit and scope ofthe invention as expressed in detailsherein described and illustratedfor the purgraduated edge whose curvature is concentric with I saidopening, and an alidade having a, pivot por tion engaging with saidpivot opening and having an index portion slidably engagin saidgraduated edge, said index portion being formed of three interconnectedsuperposed plies, the outer plies sandwiching said graduated edgebetween them and the intermediate ply having a curved inner edgeabutting said graduated edge, the pivot portion of the alidade beingalso formed of three interconnected superposed plies, the outer pliesoverlying said pivot opening and sandwiching said frame between them andthe intermediate ply constituting a journal snugly accommodated withinsaid pivot opening, the body of the alidade being of one piece with oneof the outer plies of the index portion and'with the corresponding outerply of the pivot portion.

2. In a sextant, a frame having an edge portion formed of threeinterconnected superposed plies, a slot in said edge portion, andatscreen pivotally mounted in said slot for swinging movements into andout of the optical axis of the sextant, one wall of said slotbeingdefined by aligned shoulders formed on two of said plies, the oppositewall of said slot being defined by an opposed shoulder formed on thethird ply, said third ply being the intermediate one of the three plies.

I IJOHN v. KORE.

